Verizon DC Distribution Standards - 2011

Verizon Wireline Standard VZ-STD-26.33.10

October 2011

NOTICE

Not for use or disclosure outside the Verizon Companies except under written agreement.

DC Power Engineering Standard

Part 2 of 3

DC Distribution Engineering Standard

VZ-STD-26.33.10

This Document Supersedes VZ-292-100-000

and VZB STD-022-0003

REVISION 1.0

ISSUED OCTOBER 21, 2011

Verizon DC Power Engineering Standard VZ-STD-26.33.10

DC Distribution Engineering October 2011

NOTICE - Not To Be Disclosed Outside Verizon. Without Written Agreement. Page 2 of 36

CONTENTS PAGE

1.0. Revisions ..................................................................................................................................4

1.1. Purpose and Scope ..................................................................................................................4

1.2. Disclaimer ................................................................................................................................5

1.3. Regulated and Non-Regulated Facilities...............................................................................5

1.4. Additional Standards Requirements.....................................................................................6

1.5. Approved Products .................................................................................................................6

2.0. Primary and Secondary Power..............................................................................................7

2.1. Running Direct Feeds from Power Plants or Using a Secondary Power Source ..............7

2.2. Intermediate Distribution Bays and Intermediate Fuse Panels .........................................7

2.3. Feeding Equipment from the Main Power Board or BDFB...............................................7

2.4. Design for Maximum Current Drains ..................................................................................8

3.0. Distribution..............................................................................................................................8

3.1. Voltage Drop Arrangements and Calculations ..................................................................9

3.2. Voltage Drop Calculations ...................................................................................................12

3.3. Voltage Drop Calculation Formulas ...................................................................................13

3.4. DC Power Cable....................................................................................................................14

3.5. RHH /RHW Power Cable Calculation Information..........................................................15

3.6. Minimum Conductor Gauge based upon Circuit Breaker or Fuse Size .........................16

3.7. Maximum Allowable Ampacity Based Upon Cable Size...................................................18

3.8. Power Cable Connectors ......................................................................................................18

3.9. Discharge Ground and Ground Window Term Bars........................................................20

3.10 Over Current Protective Devices........................................................................................22




3.11. Over Current Device Coordination and Sizing................................................................23

3.12. Diversity ...............................................................................................................................24

3.13. DC Cable Routing and Segregation ..................................................................................25

4.0. PRIMARY DISTRIBUTION...............................................................................................26

4.1. General...................................................................................................................................26

5.0. SECONDARY DC DISTRIBUTION BDFB (BDCBB)..................................................27

5.1. General...................................................................................................................................27

5.2. BDFB (BDCBB) Requirements ...........................................................................................27

5.3 Equipment Powering Schemes..............................................................................................28

5.4 Powering ORd Equipment...................................................................................................28

5.5 Load Balancing Simplex and Duplex Power .......................................................................30

5.6 Relay Rack Equipment Fuse/Breaker Panels .....................................................................32

5.7 Monitoring and Alarming .....................................................................................................32

5.8 Battery Returns in BDFBs ....................................................................................................33

5.9 Power to Collocated Equipment ...........................................................................................33

6.0 Definitions...............................................................................................................................34

7.0 REFERENCE DOCUMENTS..............................................................................................36

7.1 General....................................................................................................................................36

7.2 Telcordia Documents .............................................................................................................36

7.3 Industry Documents and Standards ....................................................................................36




DC DISTRIBUTION ENGINEERING STANDARD 1.0. Revisions

This document supersedes VZ-292-100-000 and is part 2 of 3 documents that comprises the total DC Power Engineering Standard. This document is to be used in conjunction with Battery Engineering Standard VZ-STD-26.33.13 and DC Power Plant Engineering Standard VZ-STD-26.33.23. Whenever this practice is reissued, the reason(s) for reissue will be provided in this paragraph.

Issue 1.0 New DC Distribution Engineering Standard for combined Verizon Telecom and Verizon Business.

1.1. Purpose and Scope 1.1.1. This standard establishes the minimum engineering guidelines to be followed during the design of any new Verizon Wireline facility's DC Distribution system. The purpose of this document is to bring consistency to the design of DC systems where possible and to establish minimum DC engineering standards and guidelines. The guidelines of this standard are applicable to all new Verizon Wireline technical facilities and major expansions to existing facilities. This document is not applicable to Verizon Telecom outside plant facilities but is applicable to Verizon Business shelters, regens, CEVs, POPs, CPE and other outside plant facilities, exceptions and additional requirements shall be noted herein. 1.1.2. Changes made in this document and subsequent issues do not specifically mandate the upgrade of existing facilitys DC power plants to meet any new requirements specified herein unless specifically noted. Nor does it necessarily apply to additions made to existing DC power Plants. In most instances of an existing DC plant, the legacy engineering standard will continue to apply until such time that the plant is replaced. In cases where it makes engineering and fiscal sense to adopt any of the new requirement specified, then it is permissible to do so, but is not required. 1.1.3. Verizon reserves the right to revise this document for any reason including but not limited to conformity with standards promulgated by various state and federal agencies, utilization of new advances in the state of the technical arts, or to reflect changes in the design of equipment or services described herein. Liability for difficulties arising from technical limitations is disclaimed. 1.1.4. This document is not to be construed as a suggestion to any manufacturer to modify or change any of its products, nor does this document represent any commitment by Verizon to purchase any product, whether or not it provides the described characteristics.




1.1.5. The engineering requirements contained in this document have been prepared to provide DC Plant Engineering personnel (internal and external), with the general requirements that are necessary to ensure that the systems and equipment specified in the engineering order are engineered and installed in accordance with Verizon standards and that newly installed equipment operates in accordance with the manufacturers design parameters and specifications. This document is intended to supplement information provided in Telcordia GR-1502CORE, Central Office Environment Detail Engineering Generic requirements, OEM specifications, as well as other Verizon technical publications. 1.1.6. Verizon Wireline may, at its discretion, specify additional requirements for specific installations. 1.1.7. Engineering and provisioning services performed shall satisfy the major equipment, interface, and environmental requirements established in the Telcordia Central Office Environmental Detail Engineering Generic Requirements GR-1502-CORE and as outlined in this document. 1.1.8. Deviations are sometimes necessary and are referred to as non-standard design. However, nonstandard designs shall be compatible with standard equipment used in standard designs. Compatible in this sense means to function and /or fit together effectively. Approval to use a nonstandard design shall be obtained from the Verizon Wireline Standards authority [email protected] in writing, if not specified in the Scope of Work or Work Order. 1.1.9. In addition to the standards and guidelines outlined in this document, the Engineering Service Provider shall consult and adhere to the most current Verizon Wireline practices, including, but not limited to, Flashes, Technical Aids, etc.

1.2. Disclaimer

This practice was prepared solely for the use of Verizon Wireline. It shall be used only by its employees, customers, and end users when engineering, installing, operating, maintaining, and repairing Verizon Wirelines equipment, facilities, and services. Any other use of this practice is forbidden. The information contained in this practice might not be applicable in all circumstances and is subject to change without notice. By using this practice the user agrees that Verizon Wireline has no liability (to the extent permitted by applicable law) for any consequential, incidental, special or punitive damages that might result.

1.3. Regulated and Non-Regulated Facilities 1.3.1 Verizon Wireline consists of Verizon Telecom which is a regulated phone company and Verizon Business which is Non-Regulated. The requirements for regulated facilities and non-regulated facilities are not the same. As a general rule, the exemptions allowed in regulated facilities do not apply to legacy Verizon Business Facilities. Non-Regulated facilities are subject




to a more extensive review by local Fire Marshalls and Electrical/ Building inspectors and must comply with codes and requirements that are not always applicable to Verizon Telecom facilities. Such codes include but are not limited to the Uniform Building Code (UBC), International Building Code (IBC), National Electric Code (NEC), National Fire Protection Association (NFPA) and Underwriters Laboratory (UL). Particular attention to the required codes when working in existing Verizon Business facilities is required; otherwise the building could be flagged by the inspector or Authority Having Jurisdiction (AHJ). This could result in the building being shut down in a worst case scenario. 1.3.2. When designing power equipment layouts, individuals working in legacy Verizon Telecom Facilities shall adhere to the codes and requirements of that facility. All equipment must be NEBS approved and certain statutes of the NFPA and NEC do still apply along with other restrictions imposed as a result of being a regulated phone company.

1.4. Additional Standards Requirements

This Verizon Wireline DC Distribution Engineering Standard is not intended to be a standalone alone document on the topic of DC Power; it is to be used in conjunction with Verizon Wireline Battery Engineering Standard (VZ-STD-26.33.13) and DC Power Plant Engineering Standard (VZ-STD-26.33.23). Additionally, other Verizon Wireline standards such as AC, HVAC, Grounding, Firestopping as defined in IP72202, section 12, Installation and material practices and procedures shall apply. These standards include but are not limited to the following: Verizon Wireline IP 72202, Verizon Wireline facility Grounding Standard (VZ 330-100-100), Power Plant Material Standard, Flooded Battery Material Standard, VRLA Battery Material Standard, Hydrogen Ventilation Standards and Environment and Safety requirements. Additionally all other pertinent industry, state, local and federal Standards such as National Electric Code (NEC), OSHA, ANSI, IEEE, Telcordia, NEBS, state, local or federal standards and reference documents as required. The principal reference document for power plants is Telcordia's TR-NWT-000154 Generic Requirements for 24-, 48-, 130-, 140- Volt Office Power Plant Control and Distribution Equipment, except as specifically modified by this standard. The requirements of this standard generally supplement, rather than replace the requirements of TR-NWT-000154. In the event of a conflict between the contents of this standard and TR-NWT-000154, the contents of this standard shall take precedence.

1.5. Approved Products Only products and materials approved by the VSO standards committee for use in the respective groups network shall be deployed in Verizon Wireline. Each business group internal to Verizon Wireline (i.e., Verizon Telecom and Verizon Business) approves products for their respective facilities in their designated ordering system. Products deployed in legacy VZT and VZB facilities shall be ordered from their respective ordering system to insure only products approved




for their use are provided. While the models and manufacturers of the equipment may be common, there are different configurations approved that meet specific needs of the facility. Equipment and components shall not be cross-mixed. This requirement shall be adhered to even when a 3rd party vendor or contractor provides the equipment for Verizon Wireline use where permitted by company policy. 2.0. Primary and Secondary Power

2.0.1.DC power is distributed to central office equipment either directly from the power plant or through a secondary distribution point. Primary distribution shall be considered any cabling associated with connecting batteries and rectifiers to the main power boards and any cabling to loads that originate at the main power boards. These primary loads generally include Battery Distribution Circuit Breaker Bays (BDCBB), Battery Distribution Fuse Boards (BDFB), and any equipment that is direct feed from the power plant such as switch distribution bays (PDCs, PDFs, EWSDs, etc.). In small facilities where direct feeds to the equipment are permissible or large facilities that require feeds of 150 amps and above to be fed direct from the power plant, these types of loads will be considered as Primary Power. 2.0.2.The most commonly used secondary distribution point is the BDFB or BDCBB. For simplicity, the term BDFB will be used in this standard for all secondary distribution boards, unless otherwise noted. Any feeds originating from a BDFB to the end equipment via any other fuse or breaker panel is considered secondary power.

2.1. Running Direct Feeds from Power Plants or Using a Secondary Power Source 2.1.1. The decision whether to distribute DC power directly from the power plant, or to use a secondary distribution point (BDFB), is based primarily on the most economical and efficient use of the cabling and over current device arrangements. For example, in small, single floor technical facilities and most shelter, regen and CEV applications where the loads are in close proximity to the power plant, it is usually more cost effective to distribute power directly from the power plant. However, in larger technical facilities, that have numerous DC loads at a greater distance from the power plant, it is often more economical to use a BDFB.

2.2. Intermediate Distribution Bays and Intermediate Fuse Panels 2.2.1 Intermediate Fuse/Breaker panels located between the secondary power source (BDFB or BDCBB) and the end equipment or the associated relay rack fuse and alarm panel should be avoided on a going forward basis.

2.3. Feeding Equipment from the Main Power Board or BDFB




2.3.1 BDFBs can be used for DC feeds up to 125 amps where this is permissible per the manufacturer specifications. Under no circumstances shall a breaker or fuse be installed in a secondary distribution bay that is larger than is permissible per the manufacturer specifications.

2.3.2. BDFB feeds that are 70 amps up to 125 amps will require approval in writing from the Power Planner and/or Central Office Engineer (Building Engineer) before they are installed. A project specification or e-mail from the originating power planner that details these feeds is required.

2.3.3. See Figure 1 for Network and collocation plant voltage drop arrangements.

2.3.4. See Figure 2 for switch plants power plant voltage drop arrangements. 2.3.5. See Figure 3 for voltage drop arrangement for loads 150 amps or greater.

2.4. Design for Maximum Current Drains 2.4.1. DC distribution feeder components include cable, over current devices, bus bar, etc., and must be designed to handle the maximum current drains of the equipment being powered. The maximum current drain is also referred to as the List 2 drain and is higher than the measured drain at float voltage. List 2 drains shall be considered the current draw at the end voltage of the equipment. The components (breakers, fuses, cable) must also be designed to handle the additional load that will be added when a failure occurs in switched (ORd power) redundancy equipment. NOTE: Legacy Verizon Telecom calculators used a theoretical List 2 current of 118% (1.18) of the equipment float current. 3.0. Distribution

3.0.1. All power plant distribution systems must comply with the generic requirements of the Telcordia Network Equipment Building Systems (NEBS) document. Installations must conform to a minimum of seismic Zone 1 requirements, or to the seismic requirements of the specific geographic region. In addition to the technical requirements specified in this standard, the distribution systems must comply with the National Electrical Code (NEC), UL, state and local codes as required. 3.0.2. For planning and engineering purposes, the maximum allowed current (actual) on any distribution over-current protective device (OCP) feeding load sharing branch circuit equipment at float voltage under normal conditions ("A" & "B" distribution paths are intact and operational) is 40% of the OCP device rating (e.g., a 400-Amp fuse is limited to 160 Amps under normal conditions).




3.0.3. When cabling is installed into the main power board or any secondary distribution bay or panel from the top, the fuse or breaker positions shall be assigned from the bottom most panel of the bay and from the further most fuse position and subsequent assignments shall grow upward in the bay as applicable. This will be reverse for bottom fed bays.

3.0.4. The fuses or breakers associated with the A and B feeds to an individual piece of equipment from the main power boards shall be separated from each other as far as practical internal to the power board but at minimum they shall not originate on the same fuse or breaker panel. Where all the fuse or breaker positions originate from a common bus or panel in the power board, the fuses or breakers associated with the A feeds shall not be directly adjacent to the fuses or breakers associated with the B feeds of any single load. 3.0.5. Twelve inches (12) of slack should be left in all cable terminations in a high seismic zone (Zone 3 and Zone 4) to allow a certain level of movement before stressing the termination point. This is to prevent pullout of the cable from the crimp lug or damage to the termination points of the equipment. 3.0.6. Each piece of equipment shall have individual feeds. Bays, panels, or equipment are not to be daisy chained together, nor shall one set of DC feeds be tapped down to multiple bays. 3.0.7. All DC power cable distribution runs shall contain an equal number of positive and negative conductors of equal size. 3.0.8. The maximum length of cable left unsupported is 3 feet for 4/0 cable and larger. 3.0.9. A capacitor pre-charge function shall be provided upon request of the engineer for the distribution fuse/CB positions, prior to closing the breaker or energizing the fuse.

3.1. Voltage Drop Arrangements and Calculations

3.1.1. In addition to all DC Power cabling needing to meet current carrying capacity requirements, it is also required that they meet the requirements for voltage drop. The maximum allowable voltage drops between the various components and specific points of distribution in the DC system are defined in the figures below. Voltage drop is usually expressed in VD one way or loop (to and from) on associated plant schematic drawings. 3.1.2. Verizon has adopted a loop voltage drop of 1.75 volt DC maximum between the Power Plant Main Distribution Board and network/collocate equipment as a standard. Installation of a BDFB will require that network equipment be engineered with a loop volt drop of 1.25 V from the main power board to the BDFB and a loop volt drop of 0.5 V from the BDFB to the network equipment. See Figure 1 for allowable voltage drops. 3.1.3. Verizon switch power plant applications has a loop voltage drop of 2.0 volt DC maximum between the Power Plant Main Distribution Board and switch equipment as a standard.




Installation of a BDFB will require a loop volt drop of 1.0 V from the Main Power Board to the BDFB and a loop volt drop of 1.0 V from the BDFB to the switch. See Figure 2 for allowable voltage drops. 3.1.4. Mixed use power plants where permitted per the DC power plant engineering standard (VZ-STD-26.33.23), shall maintain the required maximum loop voltage drops based upon the equipment type as specified in Figures 1 for network and collocation with an end voltage of 1.75 VPC and Figure 2 for switch equipment with an end voltage of 1.88 VPC. (Ex: BDCBBs powering network equipment fed from a mixed use plant that has a 1.88 VPC end voltage due the switch, shall still use the same maximum loop voltage drop of 1.25 V from the plant to the BDCBB and the 0.5V loop drop from the BDCBB to the end equipment as specified for network plants with a 1.75 VPC end voltage) 3.1.5. Power loads of 150 amps or greater must be fed from the main power board. See Figure 3 for allowable voltage drops. Figure 1: The following voltage drop arrangement shall be used for network and collocation plants (end voltage of 1.75 VPC).

MPBRectifier Battery EquipmentBDFB

orBDCBB

0.25 Batt

0.25 Rtn

0.625 Batt

0.625 Rtn

0.25 Batt

0.25 Rtn

0.5 V Loop 0.5 V Loop1.25 V Loop

Eq. Bay Fuse Panel

DC Generation Area Verizon Standard 1.75 Voltage Loop Sized per Table 2

Rectifier - converts AC to DC current to charge battery and provide DC current to load. For rectifier cable sizing refer to the rectifier manufacturer documentation. Battery - stores DC current and provides backup DC current. MPB Main Power Board is the main DC power distribution and control point. BDFB/BDCBB - secondary DC power distribution point used for network or collocation applications and can contain either fuses or circuit breakers. Feeds out to the equipment or fuse panels shall not exceed 125 amps.




Equipment Bay or Fuse Panel - located within an equipment bay and provides DC power via fuses or circuit breakers to equipment located within the bay. If the load is 150 amps or greater, the main feed should come from the main power board. Equipment network equipment. If the load is 150 amps or greater, the main feed should come from the main power board.

Figure 2 The following voltage drop arrangement shall be used for switch plants (end voltage of 1.88 VPC).

Rectifier - converts AC to DC current to charge battery and provide DC current to load. For rectifier cable sizing refer to the rectifier manufacturer documentation. Battery - stores DC current and provides backup DC current. MPB Main Power Board is the main DC power distribution and control point. BDFB - is a secondary DC power distribution point and can contain either fuses or circuit breakers. Feeds out to the equipment or fuse panels shall not exceed 125 amps. PD-x - is a secondary DC power distribution point and can contain either fuses or circuit breakers. Used for switching applications (5ESS, DMS, GTD-5, etc.). Equipment Bay Fuse Panel - located within an equipment bay and provides DC power via fuses or circuit breakers to equipment located within the bay. Equipment switching equipment.

Figure 3: Voltage drops for direct feeds to equipment bay.




MPBRectifier Battery Equipment

0.25 Batt

0.25 Rtn

0.875 Batt

0.875 Rtn

0.5 V Loop 1.75 V Loop

DC Generation Area Verizon Standard 1.75 Voltage Loop

Loads 150 amps or greater fed from MPB

Eq. Bay Fuse Panel

Rectifier - converts AC to DC current to charge battery and provide DC current to load. For rectifier cable sizing refer to the rectifier manufacturer documentation. Battery - stores DC current and provides backup DC current. MPB Main Power Board is the main DC power distribution and control point. Loads of 150 amps or greater must be fed from the MPB. Equipment Bay Fuse Panel - located within an equipment bay and provides DC power via fuses or circuit breakers to equipment located within the bay. Equipment switching equipment.

3.2. Voltage Drop Calculations 3.2.1. Voltage Drop Calculations shall be calculated at the following ampacity based upon equipment type as follows:

(A) Batteries to Powerboard: Voltage drop calculations shall be performed at 100% of the manufacturers specified constant current rating for the battery type at the specified end voltage and design reserve time. The required voltage drops as specified in this standard shall be maintained. Minimum cabling size and or quantity of cables shall meet Verizon Wireline cable ampacity specifications per Table 3 at the three conductor 75 degree C rating for the cable size used, as specified in 2008 NEC Table 310.16.

(B) Load Sharing Equipment Feeds: Any branch circuit used to feed load sharing equipment via a Powerboard, BDFBs, Intermediate Distribution Bays (IDB), Load Center and Fuse Panels shall use 50% of the fuse or breaker size feeding the individual branch circuits for voltage drop calculations. (e.g., a 400 amp feed from a Power Board to BDFB will use 200 amps for calculating voltage drop at the specified allowable voltage drop). Required voltage drops as specified in this standard shall be maintained. Minimum cabling size and or quantity of cables




shall meet Verizon Wireline cable ampacity specifications per Table 3 at the three conductor 75 degree C rating for the cable size used.

(C) Non-Load Sharing Equipment: Any branch circuit used to feed Non-Load Sharing equipment via a Powerboard, BDFBs, Intermediate Distribution Bays (IDB), Load Center and Fuse Panels shall use 80% of the fuse or breaker size feeding the individual branch circuits for voltage drop calculations. (e.g., 60 amp feed from a BDFB to the end equipment will use 48 amps for calculating voltage drop at the specified allowable voltage drop). Required voltage drops as specified in this standard shall be maintained. Minimum cabling size and or quantity of cables shall meet Verizon Wireline cable ampacity specifications per Table 3 at the three conductor 75 degree C rating for the cable size used.

Note: See section 3.11 for Over Current Device Coordination and Sizing.

3.3. Voltage Drop Calculation Formulas

3.3.1. The following formulas shall be used for voltage drop, cable sizing and maximum distance calculations when using cable. Once the cable size is determined based upon the expected equipment current draw, the cable voltage drop must be verified. Voltage drop can be calculated for loop or one way distances. Additional cables or an increase in cable size may be required to meet the cable voltage drop requirement. The formulas provided below are for loop distance and voltage drop calculations where the following parameters apply:

Amps: Amps are based upon items (A), (B), and (C) in section 3.2 Voltage Drop Calculations. The amps will be the same for either loop or one way calculations.

Circular Mills: The required cross sectional area in circular mils to maintain the specified voltage drop at the specified loop distance in feet, or the specified circular mils of the RHH/RHW cable per Table 1 of this standard. The required circular mils may necessitate multiple cables per polarity to achieve the desired voltage drop. The same size and quantity of cables must be equal in both legs (battery and battery return) of the DC circuit.

Feet (Loop): The total distance in feet of the feed being calculated. Loop feet include the distance from the source to the destination and back to the source. Where one way voltage drop calculations are required, the distance in feet specified shall be the one way distance from the source to the destination.

Voltage Drop (Loop): The amount of volts lost for the specific feed being calculated. Voltage losses are based upon the amount of current, the resistance of the cable, and the distance of the destination from the source. Where one way footage is used for calculations, the voltage drop calculated will be the voltage drop in one leg of the DC Circuit only. Total voltage drop takes in account the losses in the battery and battery return leads of the given circuit.

Constant for Copper Cable: Defined to be a constant of 11.1.

Formula 1 = Solving for Circular Mils (Cable Size):




Circular Mils = (11.1 * amps * feet (loop)) / Voltage drop (loop)

Formula 2 = Solving for Voltage Drop:

Voltage Drop = (11.1 * amps * feet (loop)) / Circular Mils)

Formula 3 = Solving for allowable foot distance:

Feet = (Circular Mils * Voltage Drop (loop)) / (11.1 * amps)

Note: Power calculators are available on the TSS Power web at:

http://power.verizon.com/Calculator.htm

The Verizon Business secondary power calculator is on the TFES website at:

http://tfes.mcilink.com/coeps/Loop%20Length%20Spreadsheet/Loop%20Calculator%20C.htm

3.4. DC Power Cable

3.4.1. All DC power cable installed on cable racks for Primary and Secondary Power must be RHH/RHW stranded copper or clad copper (tinned stranding) for all new facilities and major expansions to existing ones. RHH/RHW shall be provided from a Verizon approved cable supplier. Only non-halogenated, low-smoke, sulfur and lead-free products are to be used. The outer covering can be either a fabric-braiding or a thermosetting material.

3.4.2. RHH/RHW cable to all loads (Primary and Secondary) shall be B Strand or Code type. RHH/RHW cabling direct to battery string post or post plates and rectifier drops from overhead busbar into rectifier bays should be I strand /Flex. DLO (Diesel Locomotive) type cable is not permitted. The I strand cable relieves stress on battery posts. 3.4.3. Code or B Strand is permissible to batteries where main or battery term bars are provided. Where battery term bars are used, the drops to the battery posts or post plates from the term bars should be I Strand/ Flex. 3.4.4. Legacy VZB sites will continue to use Red and Black THHN for Secondary cable in facilities that utilize hanger brackets to route cable to the individual loads from the BDFBs or BDCBBs. Where dedicated cable racks are deployed for running secondary cable RHH/RHW B strand / Code cable shall be used 3.4.5. Although color-coding of DC battery supply and battery return cables is not required, standard gray is preferred. However, if colored cabling is required, the following shall apply: Red: 48V conductors

http://techweb.verizon.com/Public/Power/Calculator.htmhttp://tfes.mcilink.com/coeps/Loop%20Length%20Spreadsheet/Loop%20Calculator%20C.htm




Blue: +/-24V conductors Black: 48V or 24V battery returns. 3.4.6. Battery and battery return leads must be run in pairs to ensure close magnetic coupling which will help reduce noise. 3.4.7. Ampacity of the cable shall exceed the load and over current protection device size and comply with Tables 2 and 3 of this standard. 3.4.8. Cable insulation (RHH/RHW) that is rated for 90 degree C from the manufacturer cannot be used to that ampacity/temperature per the NEC code. The 90 degree C rating for a given cable can only be used when it is part of a de-rating calculation that ends up with the cable ampacity meeting the 75 degree C or less rating for cable rack, wire way, or conduit applications where three or more conductors are contained in or on them. Where the ampacity at the 75 degree C rating is used for cable calculations, additional derating for the quantity of cable on a cable rack is not required. 3.4.9. When running DC feeds in a conduit or wireway, the maximum allow fill rate shall be adhered to as specified in the NEC code along with all applicable de-rating factors. Wireways shall be sized to accommodate all present and future cabling required. (See 2008 NEC Article 310.15 (B)(2) and Table 310.15(B)(2)(a)) 3.4.10. Open air ratings for cable only apply when the conductor is not directly paired with any other cable. Conductors should be separated by at least the width of the conductor in question in all directions on the cable rack (or other support method) to be considered open air and must not have multiple layers of cable on top of each other without adequate space left between them. 3.4.11. While flex cable (I strand) contains more circular mils then the corresponding size of code cable (B strand), there is no allowable difference in ampacity that is recognized by NEC code. For example, a 4/0 Flex (I Strand) cable is actually 250,000 circular mils where as a 4/0 Code cable is 211,600 circular mils. While there is no difference in ampacity, the additional circular mils may affect the voltage drop calculation. 3.4.12. All DC power cable installed between the battery string(s) and power plant components shall be in compliance with GR 347 CORE, Generic Requirements for Central Office Power Wire." All electrical conductors, connectors, and bus bars shall be copper or tinned copper.

3.5. RHH /RHW Power Cable Calculation Information

3.5.1. Use the following generic information for RHH/RHW cable calculations. While the information below is specifically for B strand RHH/RHW, the values can be used for I strand/flex cable as well. Note: Actual cable data may vary by manufacturer.




3.5.2. For transitional purposes (i.e. non-permanent) the Open Air Rating and Average Three Conductor ratings in Table 1 may be used as applicable.

Table 1: RHH/RHW Cable Characteristics RHH/RHW Cable (Code/B Strand) Characteristics

Wire Size

Three conductor Rating @

75 C (amps)

Open Air Rating @

75C (amps)

Average three Conductor Rating in Open Air

(amps)

Circular Mills

Weight Per Foot

(LBS)

Diameter Over

Insulation (Inches)

Bend Radius (Inches)

14 15 20 17.5 4110 0.026 0.19 0.95

12 20 25 22.5 6530 0.035 0.21 1.05

10 30 40 35 10380 0.049 0.24 1.2

8 45 65 55 16510 0.084 0.31 1.55

6 65 95 80 26240 0.126 0.4 2.0

4 85 125 105 41740 0.19 0.45 2.25

2 115 170 142.5 66360 0.275 0.51 2.55

1/0 150 230 190 105600 0.443 0.63 3.15

2/0 175 265 220 133100 0.54 0.68 3.4

4/0 230 360 295 211600 0.814 0.75 3.9

350 MCM 310 505 407.5 350000 1.31 0.98 4.9

500 MCM 380 620 500 500000 1.815 1.12 5.6

750 MCM 475 785 630 750000 2.7 1.34 6.7

Where:

a) Three Conductor Rating 75 Degree C: Used where there are multiple conductors and could be multiple layers of cable on cable rack (or bundle) and laced together.

b) Open Air Rating 75 Degree C: Single Conductor in Open Air (no conductors adjacent) c) Average 3 Conductor Rating and Open Air: one layer of cable on rack with cables side by side d) 90 degree C rating: Where the RHH/RHW cable insulation is rated for 90 degree C. Do not use this rating

without applying de-rating values as specified in 2008 NEC Article 310.15(B)(2). Resulting allowable ampacity must calculate out to less then or equal to the 75 degree three conductor rating to be able to be used.

3.6. Minimum Conductor Gauge based upon Circuit Breaker or Fuse Size 3.6.1. The following table shows the minimum gauge RHH/RHW conductor that can be terminated on a circuit based upon the breaker of fuse size feeding it. The following does not account for voltage drop. It is the minimum required to meet NEC code.

Table 2: CB/Fuse Size and Minimum Conductor Gauge




SECONDARY POWER CB/Fuse Size (AMPS)

MINIMUM ALLOWED Conductor Gauge (AWG)

15 14

20 12

30 10

40 8

50 8

60 6

70 4

80 4

90 2

100 2

125 2 (Note 1)

PRIMARY POWER CB/Fuse Siz e (AMPS)

MINIMUM ALLOWED Conductor Gauge (AWG/MCM)

150 1/0

200 4/0

225 4/0 (Note 1)

250 350 MCM

300 350 MCM

400 500 1) MCM (Note

500 750 MCM (Note 1)

600 (2) ty 350 MCM per polari

800 (2) 5 1) 00 MCM per polarity (Note

Note 1: NEC Arti 0-3b allowance cle 24




3.7. Maximum Allowable Ampacity Based Upon Cable Size

3.7.1. Maximum Allowable Ampacity for Cable Size The maximum allowable ampacities below are based upon 2008 NEC Table 310.16. They are the three-conductor rating at 75 degree C for RHH/RHW cable. This will be the most applicable rating for multiple cables ran on a cable rack and laced together.

Table 3: Cable Size and Maximum Allowable Ampacity

GAUGE AMPACITY GAUGE AMPACITY

14 15 1/0 150 12 20 2/0 175 10 30 4/0 230 8 45 250 255 6 65 350 310 4 85 500 380 2 115 750 475

3.8. Power Cable Connectors

3.8.1. General Use Compression Lug Requirements 3.8.1.1.. See Verizon Battery Standard VZ-STD-26.33.13 for additional information regarding lug requirements for terminations to battery post or post plates. 3.8.1.2. .All power and ground cable connectors must be two-hole connectors, tinned/plated copper, be non-reversible, gas tight compression type, and have an inspection hole. They must be purchased from Verizon Wireline approved suppliers, including Burndy, and Thomas & Betts. The use of mechanical or Smart Head type connectors is prohibited. 3.8.1.3. All connector crimps must be full circumference (Burndy Dies) or hexagonal (Thomas and Betts Dies) type crimps, with the die listing clearly legible for inspection. Covering of the die listing is prohibited. Pinch crimps are not permitted. All crimps must be made per the manufacturers specifications. 3.8.1.4. Approved lugs must be properly sized for the application and for the cable size and stranding as specified by the manufacturer and the appropriate dies and tools shall be used for crimping. The completed assembly (lug, cable, tool and die) must result in a UL Listed assembly. Code cable lugs and taps shall not be used on flex strand cable unless this is permitted and specified by the manufacturer. Only Burndy and Thomas & Betts (T & B) are approved for use in the Verizon Wireline network.




3.8.1.5. Lugs or cabling shall not be field modified to fit. Stranding of the cable shall not be cut or removed to fit a lug that it is not designed for, nor shall lugs be bent or drilled to accommodate the required termination by installation personnel. The appropriate cable and compression fitting shall be used to fit the application. 3.8.1.6. Burndy and T & B dies have been cross-certified by UL to work on each others lugs and tooling. There are certain combination of taps, splices and dies that are not permitted. Consult Burndy and T & B for the approved combination of connector and dies. 3.8.1.7. Two-hole lug connectors are required on battery return conductors. 3.8.1.8. All compression lugs, one-hole and two-hole, shall be equipped with Inspection Windows for all applications except for direct termination to the battery posts or battery post plates as required. See Verizon Battery Standards VZ-STD-26.33.13 for battery termination information.

3.8.1.9. Narrow tongue lugs are not to be used for general purposes and can be used only where the termination as provided from the equipment manufacturer requires it. The use of narrow tongue lugs to terminate cables larger then the provided terminations allows using a standard width lug is prohibited. 3.8.1.10. Compression lugs shall have a minimum of two crimps for all applications. 3.8.1.11. Clear heat shrink shall be used to cover the barrels of lugs after crimping provided that the die listing can be easily distinguished after the heat shrink is applied. Additionally, clear heat shrink shall be applied to the barrel of the lug where there is minimal clearance to adjacent lugs or where there is potential of a short. 3.8.1.12. Back to back connections of lugs on any busbars using through bolt terminations are generally permitted for all type of connections. Back to back terminations should be avoided for devices or equipment where they could cause a single point of failure. 3.8.1.13. On busbars, always leave one set of holes unused for transitional and maintenance purposes.

3.8.2. Taps and Splices

3.8.2.1. H-taps shall be used for primary and secondary power runs. Reducing inline butt splices for secondary power are permitted for use in legacy Verizon Business facilities that utilize L brackets for supporting Secondary Power Cable. Only Verizon Wireline approved taps and splices can be used. Taps and splices shall be tinned/plated copper and have clear covers. Inline reducing splices for cable runs consisting of a single cable per polarity only. Multiple cable runs per polarity that must be reduced in size or quantity requires H-Taps.




3.8.2.2. Only Burndy or T & B H-taps shall be used for DC Power Cabling. Only Burndy inline reducing splices are approved for use in Verizon Business legacy facilities.

3.8.2.3. Butt Splices are not permitted and C taps shall not be used for power runs. C taps are permissible for grounding only but are not preferred. 3.8.2.4. All taps and splices shall be equipped with clear covers and or clear heat shrink as specified by the manufacturer. 3.8.2.5. Burndy and T & B dies have been cross-certified by UL to work on each others lugs and tooling. There are certain combination of taps, splices and dies that are not permitted. Consult Burndy and T & B for the approved combination of connectors and dies. 3.8.2.6. Approved taps and splices must be properly sized for the application and for the cable size and stranding as specified by the manufacturer and the appropriate dies and tools shall be used for crimping. The completed assembly (lug, cable, tool and die) must result in a UL Listed assembly. Code cable lugs and taps shall not be used on flex strand cable unless this is permitted and specified by the manufacturer. Only Burndy and Thomas & Betts (T & B) are approved for use in the Verizon Wireline network. 3.8.2.7. The cable, lug, splice or tap shall not be modified to fit. Stranding shall not be cut or removed to fit a lug that it is not designed for, nor shall lugs be bent or drilled to accommodate the required termination by installation personnel. The appropriate cable and compression fitting shall be used to fit the application. 3.8.2.8. When using H-taps or reducing inline, where permitted, splices or taps made to reduce a given cables size, or to reduce the quantity of cables to be terminated, the minimum size of the reduced cable size or quantity shall comply Verizon Wireline minimum cable size requirements (See Tables 2 and 3) and the NEC or any other applicable state or local codes. Under no circumstances are fewer cable(s) or a smaller gauge cable(s) to be terminated that do not meet the fuse/breaker clearing and or current carrying capability of the of the cable(s) being terminated. 3.8.2.9. A given cable run shall not contain an excessive amount of taps or splices in it. If over time, due to re-use of cable runs, the splices or taps become excessive, new cable runs to the equipment shall be provided.

3.9. Discharge Ground and Ground Window Term Bars




3.9.1. Term Bars are copper busbar assemblies that are drilled to accommodate compression type lug connections to facilitate cabling of batteries, rectifiers and power boards to establish the 48V Plant. Term Bars are commonly used to carry large amounts of current to and from the batteries, rectifiers and loads. Term Bar systems are usually exposed and non-insulated to the environment. Since the bus bar is exposed it is restricted to use only in the area of the main power complex for connecting the battery plant and rectifiers to the main power distribution board. The most popular types of term bar assemblies are as follows: 3.9.2. Discharge Ground Bars The discharge ground bar provides a collection point for all the returns of the loads fed from the power point along with the returns from the rectifiers and batteries. The discharge ground bar can be used in conjunction with a ground window and or main term bars depending upon the needs. The discharge ground bar is usually segregated into a charge and discharge section with the CO Ground connection providing the separation point. Rectifier and battery returns will be allocated to the charge section and load returns to the discharge section. It also can be used as part of the ground window. This bus shall be sized for the full ampacity of the power plant. 3.9.3. Ground Window Bars The ground window bar is required where an isolated ground plane exists. See Verizon Wireline Grounding Standards for Ground Window requirements when an Isolated Ground Plane is required. 3.9.4. Term bar assemblies are current carrying bars and must be sized in accordance with the size of the power plant or the maximum expected load that they are to carry at discharge/ end voltage. 3.9.5. Term bars can come as stacked assemblies consisting of battery and battery return or individual buses for battery or ground. All term bars shall be mounted on insulators that keep the busbar a minimum of 2-3/4 above any cable rack or framing. Additional height can be provided using more then one isolator or a larger isolator as needed. When battery and battery return are stacked assemblies, the bottom bar shall always be the battery return bar and the top bar battery. 3.9.6. Any term bars provided as part of an installation shall be designed for the expected ampacity required and be equipped with standard lug termination patterns based upon the size of cable to be terminated. Standard lug terminations are as follows: ! bolt on 5/8 centers (for cables 2ga and less), 3/8 bolts on 1 centers and " bolts on 1-3/4 centers. The use of #10 AWG bolts on 5/8 center holes shall be avoided. The spacing of the hole patterns shall be such that lugs can be mounted in each hole position without blocking adjacent positions for all reasonable expected standard lug widths. Hole spacing shall not be sized for narrow tongue lugs. Staggering the hole pattern on the top and bottom of the bar is preferred. 3.9.7. It is advisable to always leave one set of termination holes open on any type of term bar to allow for future transitions if needed.




3.9.8. Back to back connections of lugs on busbars using through bolt terminations are permitted. However, it is not advisable to use a back-to-back connection in conditions that create a single point of failure.

3.10 Over Current Protective Devices 3.10.1. The purpose of an over current protective device is to protect downstream wiring and components from overheating due to excess current. Over current protective devices must be fuses and/or circuit breakers, and will be referred to as over current or over current protective devices in this document. All over current protective devices are installed on the-48 Volt supply side of the downstream components they are protecting. 3.10.2. Main Power Board Over-Current Protection: The preferred over current protection device in main power boards are DC rated telecom type fuses. Fuses provide the best protection to the system and down stream equipment. Where possible new power plants shall include DC rated fusing as the primary over current protection device. Fuses used in any power board shall be DC rated (e.g., Bussman TPL, TPS, TPA or equivalent). While circuit breakers are more convenient because they can be reset upon tripping, the breaker can degrade and its ability to successively trip at the rated ampacity becomes questionable the more times the breaker trips. 3.10.3. Where circuit breakers above 150 amps are required in a main power board, they shall be of bolt in construction. Required distribution below 150 amps can be fuses or breakers in the main power board.

3.10.4. Two smaller over current protective devices are not to be paralleled (non-mechanically slaved) to create a larger one (i.e., using two independent 100 amp fuse or breaker positions to create a 200 amp circuit out to a load). Multi-pole breakers such as 400 amp or 600 amp breakers that have their switches mechanically slaved by the manufacturer so that all the poles trip at the same time are permitted. 3.10.5. For the purposes of this standard, all power source points (i.e., load side of any distribution bus) shall be protected by adequately sized and rated protection devices. All loads external to the power plant shall have over-current protection. The only exception is when cabling from batteries is ran un-fused on a dedicated cable rack. 3.10.6. Fuses installed on the BDFB must be DC rated cartridge type, Type GMT, Type TPS, TPA, TPL, TPN or Type 70 fuses. All feeder fuses must be DC rated, and be fast- blow types. All over current devices must be UL listed, rated for DC service and purchased from a Verizon approved supplier, including fuses from Bussman or Shawmut and circuit breakers from Airpax/Sensata or Eaton/Heinemann. 3.10.7. Engineers must provide five spare fuses for each size fuse equipped on a new BDFB or the addition of a new fuse size on an existing BDFB. Twelve spare alarm fuses must be provided for a new BDFB.




3.10.8. Engineers must provide one spare circuit breaker for each size circuit breaker equipped on a new BDCBB, and one for each new size added to an existing BDCBB. Figure 4: DC Distribution

3.11. Over Current Device Coordination and Sizing

3.11.1. Power supply circuits should be designed so that the over current device nearest to the fault will operate before any upstream over current devices. The time delay values (fast blow / slow blow) of the over current devices must be considered. 3.11.2. Breakers and fuses feeding individual branch circuits will be sized to match the planned worse case current draw of the equipment at the end voltage specified by the manufacturer. This end voltage may be lower then the designed end voltage of the power plant itself. No additional derating (125% or 150%) of the upstream breaker or fuse feeding the branch circuit is required. . Where worse case draw does not match a standard breaker or fuse size, round up to the next standard size. Under no circumstances shall a breaker or fuse smaller then the worse case load planned for be used. It must be equal to or greater in size then the planned worse case load of the equipment. 3.11.3. Breaker/fuse coordination, sizing, and placement shall be designed primarily for electrical fault protection. Under fault conditions, OCP coordination and sizing shall ensure swift circuit interruption to protect the power plant and the distribution system. Proper coordination shall also ensure that OCP tripping will begin with the closest OCP device to the fault under

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Verizon Wireline control, effectively isolating the fault from the circuit without disrupting the entire distribution system 3.11.4. Breaker Coordination will not start or originate with any internal fusing to the equipment itself, or from any fuse or breaker panel that is provided by the manufacturer or the end equipment in that rack. Only Verizon Wireline installed fuse panels will be considered for breaker coordination. Breaker coordination will originate at the last over current protective device provided by Verizon Wireline. Only breakers or fuses under direct control of Verizon Wireline shall be considered for breaker coordination.

3.12. Diversity 3.12.1. Equipment having two separate power inputs commonly referred to as A and B shall be supplied from diverse sources of power originating at the main power board. Diverse power feeders for circuits shall have no common over current protective devices, and the over current devices must have the greatest physical separation as practical. The following illustrates the two methods used to ensure power diversity. Figure 5: Power Diversity Method 1

Figure 6: Power Diversity Method 2




3.13. DC Cable Routing and Segregation 3.13.1. Battery cables that are not equipped with over current protective devices must be run on a dedicated cable rack with no other cabling, and stamped Un-fused Leads Only. 3.13.2. Primary distribution cables feeding secondary distribution loads (e.g., BDFBs) should be either run on dedicated power cable racks or segregated from secondary power cables.. 3.13.3. Grounding conductors shall not be run on DC power cable racks. 3.13.4. For economic and efficiency reasons, power cable runs should be designed to be as short and direct as possible. 3.13.5. The DC Distribution scheme for any facility shall provide A and B power distribution paths from a common source. The distribution path shall be considered the plant, bay or fuse panel directly upstream of the device in question. Whole plants, BDFBs, BDCBBs shall not be dedicated to either an A or B feed. Distribution panels internal to the given power plant, BDFBs or BDCBBs or IDBs can be dedicated to A or B feeds to the downstream equipment. 3.13.6. Diverse routing of A and B feed cables to the same end bay or piece of equipment on different cable racks is not permitted. All A and B feeds must be run paired and closely coupled on a common cable rack.

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3.13.7. All DC cabling shall be installed overhead where possible. DC conductors that are to be run under a computer floor used as a plenum (has air movement as part of a HVAC system) shall be avoided wherever possible. If it becomes necessary to run conductors under a raised floor that is used as a plenum, the cables must be plenum rated or be run in conduit or wireway that is sealed from the point they enter the raised floor to the point in which they leave the raised floor. RHH/RHW power cables can be ran under a floor in a manner similar to overhead using cable rack if not used as a plenum, but this should be avoided due to congestion issues. 3.13.8. AC and DC cables shall not be mixed on the cable rack. 3.13.9. DC Power cabling shall not be mixed with networking cable. If power and networking cable must be installed on the same rack, they shall be segregated as best as possible. 4.0. PRIMARY DISTRIBUTION

4.1. General

4.1.1. DC circuits may be powered directly from the power plant, and must conform to all of the requirements set forth in this practice. 4.1.2. DC loads greater than 125 amps must be supplied from the main power board. Main Power Distribution Boards provide power up to 600 amps per individual fuse/circuit breaker. Loads in excess of 600 amps may be powered directly from the main, un-fused power source with the use of a Fused Disconnect Switch Unit device. The figure below illustrates a typical power plant using Disconnect Switch Fused Units (DSUF). The DSUF are used in mated pairs to provide A and B power diversity. Figure 7: Disconnect Fused Switch Units

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5.0. SECONDARY DC DISTRIBUTION BDFB (BDCBB)

5.1. General 5.1.1. The BDFB and BDCBB serve as secondary distribution points for DC power delivered from a power plant to the telecommunications loads and also provide redundant power feeds to the load through the use of multiple load buses. Each load bus is individually protected for over current conditions by a fuse or circuit breaker. The maximum over current device size on a BDFB is 125 amps. 5.1.2. The use of a BDFB is usually cost effective when it is necessary to supply many smaller loads that are located relatively far away from the power plant. A BDFB will also help minimize power cable congestion at the power plant. 5.1.3. Caution should be taken when determining where to place the BDFB on the equipment floor, the engineer should plan for power cable build-up, and good access to the battery return bar mounted above the bay, if provided. 5.1.4. The Verizon field engineer, power engineer, or a suitable representative must take load readings on existing BDFB feeders prior to adding new loads to ensure the capacity of the BDFB feeder does not exceed 40% of the actual load on the current protective device.

5.2. BDFB (BDCBB) Requirements 5.2.1. The height of a standard Verizon Wireline BDFB is seven feet. For legacy Verizon Telecom facilities, under limited conditions, a nine-foot (9) or eleven-foot, six-inch (11-6) bay may be allowed. Component sections may be installed to meet framing and cable racking requirements. 5.2.2. Branch circuits 60 amps or larger shall skip adjacent fuse or breaker positions on both sides of the fuse or breaker unless otherwise specified by the Verizon Wireline Standards Authority in writing. Individuals requesting a waiver to this requirement shall submit the waiver request to [email protected]. The requesting individual shall provide the BDCBB/BDFB equipment manufacturers specific documentation showing that fuses or breakers 60 amps and larger can be mounted side by side in the specific bay being used. A waiver must be approved in advance of deploying any breakers in a manner that violates this requirement. 5.2.3. All branch circuit breakers or fuses used in BDCBB/s or BDFBs shall be installed per manufacturer specifications with regard to skipping adjacent spaces and the maximum wire and lug sizes that can be terminated. All lug widths shall be based upon standard width lugs (not narrow tongue) as provided by the Verizon Wireline Approved lug vendors (Burndy and T & B).

mailto:[email protected]




5.2.4. Breakers shall be Electrical Trip Only in BDCBBs and Power boards (where provided). This will provide an alarm only if the circuit is electrically overloaded. Breakers that alarm when manual shut off shall not be used.

5.2.5. All new BDCBB/BDFBs shall utilize bullet type breakers or fuse modules.

5.2.6. BDCBBs, BDFBs or any device such as a fuse or breaker panel, that then powers downstream loads, shall be sized to match the anticipated worse case load of the equipment they are intended to serve, up to the buss rating of that distribution device as specified by the manufacturer. Where the load is unknown at the time of engineering, the fuse or breaker feeding other distribution devices shall be sized to the anticipated load of the end equipment or downstream device plus all reasonable growth. 5.2.7. Verizon Business BDCBBs and BDFBs utilized in legacy facilities will be limited to bays with no more then 4 load panels physically installed. Bays bay may be capable of more load panels but these shall be blanks. The BDCBBs and BDFBs shall be fed with no more then a 400 amp fuses or breaker per load. This is due to design restrictions of the cable rack structure and cable congestion issues internal to the bay due to internal ground bars being required internal to the bays. If additional capacity above 400 amps per load is required, a written waiver is required. Individuals requesting a waiver to this requirement, shall submit the waiver request to [email protected]. A waiver must be approved in advance of deploying any BDCBB or BDFB in a manner that violates this requirement 5.2.8. Legacy Verizon Business Facilities, with few exceptions, are not set up for the use of external battery return bars associated with the BDFBs in the technical area. External battery return bars shall not be deployed for BDFBs in existing Verizon Business facilities that currently are not using them without approval from TFES. Deploying external ground bars may cause problems with cable racking, framing, cable pileup blocking access to other bays, lighting and or access to the bays for other types of cabling or fiber / fiber duct that must be used.

5.3 Equipment Powering Schemes 5.3.1. Loads shall be balanced among the available feeds of the power board, BDFB or Equipment Bay Fuse Panel based upon whether the equipment is Load Sharing (ORd), Duplex, or Simplex. Load Sharing or ORd feeds are feeds in which upon a failure of one of the feeds (either A or B) causes the current to double in the remaining feed.

5.4 Powering ORd Equipment 5.4.1. Load assignments on multi-load BDFBs must be balanced out over all BDFB loads to ensure diversity.

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5.4.2. A and B Load Sharing (ORd) feeds terminating on the same equipment shall be fed from different load panels in the BDFB from which they are served. BDFB load panels serving ORd equipment shall not be loaded greater than 40% of the over-current protective device rating. The Main Power Board Fuse serving the BDFB load panel shall not be loaded greater than 40% of the over-current protective device rating. 5.4.3 The following illustrates the two methods used to ensure ORd power load balancing.

Figure 8: ORd Method 1




Figure 9: ORd Method 2

5.5 Load Balancing Simplex and Duplex Power 5.5.1. Equipment with simplex input power shall be fed from different load panels in the BDFB to balance the load. BDFB load panels serving simplex equipment shall not be loaded greater than 80% of the over current protective device rating. The Main Power Board fuse serving the BDFB load panel shall not be loaded greater than 80% of the over current protective device rating.

5.5.2. Duplex equipment with A and B loads terminating on the same equipment shall be fed from different load panels in the BDFB from which they are served. BDFB load panels serving duplex equipment shall not be loaded greater than 80% of the over current protective device rating. The Main Power Board Fuse serving the BDFB load panel shall not be loaded greater than 80% of the over-current protective device rating.

5.5.3. The following illustrates the two methods used to ensure simplex and duplex power load balancing.




Figure 10: Simplex/Duplex Method 1




Figure 11: Simplex/Duplex Method 2

5.6 Relay Rack Equipment Fuse/Breaker Panels 5.6.1. Relay rack fuse or breaker panels shall be sized to and cabled for the anticipated load of the equipment it is intended to serve and powered accordingly. Allowances for growth shall be accounted for. Relay rack fuse or breaker panels shall not be fed from an over current protection device larger then its maximum allowable bus rating as specified by the manufacturer. 5.6.2. Relay rack fuse or breaker panels can be utilized to support loads in the bay where it is located or the directly adjacent bays only. Relay rack fuse or breaker panels are not to be used to feed equipment across aisle or relay racks further then one bay location in either direction from where it resides in the row . The racks and equipment served shall be properly labeled to indicate where the power source is located.

5.7 Monitoring and Alarming

5.7.1 Main Power Board Current Drain Monitoring




5.7.1.1. The current drain on feeders that supply power to BDFB/BDCBB only must be monitored using the power plants monitoring device. 5.7.1.2. Threshold levels must be set on the feeder drain monitors. At 40% capacity, a lamp must illuminate and a major alarm must warn that the feeder is approaching the threshold. This indicates that an additional BDFB installation should be planned and no further distribution will be allowed from that feeder. At 50% capacity, a critical alarm must be generated, indicating the maximum capacity of the feeder has been reached and a project should be initiated to redistribute loads to reduce the load to 40% capacity or less and provide additional feeders. In no case will additional loads be added to this feeder after it has reached 40% capacity. 5.7.1.3. All DC power feeders over 100 amps should be equipped with threshold monitors that will transmit an alarm when the load reaches a predetermined threshold. It is recommended that all existing BDFBs, and other large power feeders, without threshold monitors be retrofitted with the monitors. Feeders over 100 amps that are not equipped with threshold monitors should be manually measured semiannually, or as maintenance practices require.

5.8 Battery Returns in BDFBs 5.8.1. A battery return bus bar assembly shall be provided. It may be mounted externally from the BDFB, where possible, to reduce the cable congestion typical to older BDFBs, and to reduce the potential for shorting out the battery and return bars. As an option, an internal battery return bar assembly can be provided. The battery return bar must be copper or clad copper, and pre-drilled and tapped to accept two-hole, crimp type (compression) copper lugs. 5.8.2. Battery return conductors must equal or exceed the over-current protection device rating of its paired supply conductors.

5.9 Power to Collocated Equipment 5.9.1. Collocated equipment belonging to a Competitive Local Exchange Carrier (CLEC), or other entity, and is physically placed in a Verizon Wireline Technical Facility via the formal Collocation Application Process. Power supplied to collocated equipment is subject to the same technical requirements as power supplied to Verizon equipment. Verizon requires a joint safety inspection of all collocation installations prior to installing over current devices to supply power to the collocation equipment.




6.0 Definitions

Glossary of terminology and acronyms pertaining to DC distribution: AHJ: Authority Having Jurisdiction. Defined in the NEC 2007 as an organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, and installation, or a procedure. Battery Distribution Fuse Board (BDFB) - is a distribution device frame that accepts feeders from -24, -48, or +130 volt battery plants and distributes the power through branch over-current devices to power multiple fuse panels or major pieces of equipment. The BDFB is designed to take the place of the Main Power Board of the Power Plant on the floor(s) of the equipment room(s) because of the distance factors and voltage drop from the Main Power Board. It is usually located near the equipment it serves. This term BDFB will be used throughout this document and will interchangeably include the circuit breaker version commonly called the Battery Distribution Circuit Breaker Board (BDFB). Circuit Breaker - A device designed to safely open and close a circuit and protect it against overloads. The resettable device automatically opens the circuit when its capacity is exceeded. Duplex Equipment Network equipment powered by two power feeds. This equipment will have one feed powered from the A feeder and the other power feed powered from the B feeder. Feed - the single power distribution cabling (conductors) necessary to deliver -48V DC power to the equipment. Each feed will have a battery conductor from the over-current protective device (fuse/circuit breaker) to the equipment and a battery return conductor from the load to the common return at the power distribution point. Feeder Term that is often used interchangeably with Feed. Feeder Drain Current Alarm Alarm generated when the drain on a particular feeder has increased above 80% of the current rating of the fuse or circuit breaker. Float Voltage The normal operating voltage of a power plant. It is specified to give the maximum battery life and capacity. Fuse - A device designed to safely open a circuit and protect it against overloads. The device irreversibly opens the circuit when its capacity is exceeded. Fuse Panels - A distribution device designed to power equipment located within the same bay or frame.




List 2 Current Drains Maximum current drain of equipment under low voltage conditions. Used for sizing cabling and over current protective devices. Network Plant: Network plants were commonly known as toll plants in VZT terminology and are plants that do NOT provide power to any TDM switch equipment (e.g., DMS, 5ESS, etc.). Or'd Load A load that obtains powering redundancy by using multiple feeders that are feed internally to a common power module through a pair of ORing diodes. If one feeder fails the entire load will be assumed by the remaining feeder. Each feeder must be capable of supplying the entire load. Overcurrent protective device - a fuse or circuit breaker. Simplex equipment network equipment powered by a single power feed. Simplex equipment in the same relay rack should be feed from equally from A and B feeds to balance the loads. Voltage Drop (DC Feeder) - a reduction of the supply voltage that is delivered to the load due to the resistance in the cable and the current through the cable.




7.0 REFERENCE DOCUMENTS

7.1 General The documents listed in this section are considered reference and source documentation for the guidelines and standards presented above. This is the Verizon Standard for Central Office Distribution. This document establishes minimum standards for the Verizon Company. It does not preclude individual States or localities from exceeding these standards. This standard is part 2 of 3 documents that comprise the total DC Power Engineering Standard. This document is to be used in conjunction with: Verizon Wireline DC Power Plant Engineering Standard - VZ-STD-26.33.23 and Verizon Wireline Battery Engineering Standard - VZ-STD-26.33.13

7.2 Telcordia Documents The following Telcordia documents shall apply, unless specifically modified by this standard:

TR-TSY-000406 DC Bulk Power Systems for Confined Locations TR-EOP-000063 Network Equipment Building Systems (NEBS) TR-NWT-000347 Generic Requirements for Central Office Power Wire TR-TSY-000500 LATA Switching Systems Generic Requirements

GR-512-CORE Reliability

GR-513-CORE LSSGR: Power

GR-63-CORE Network Equipment Building Systems (NEBS)

GR-1089-CORE Electromagnetic Compatibility and Electrical Safety

7.3 Industry Documents and Standards The following documents may apply, as required, unless specifically modified by this standard: National Electric Code (NEC).Latest Version American National Standards Institute (ANSI)..All Applicable Standards Underwriters Laboratories (UL) All applicable Standards Compliance with the following Telcordia (Bellcore) documents and industry standards is also required:

ANSI/ASQC Q9000-1 Quality Management and Quality Assurance Standards ANSI/ASQC Q9001 Model for Quality Assurance in Design/Development and Production ANSI/ASQC Q9003 Model for Quality Assurance in Final Inspection and Test

DC Power Engineering StandardPart 2 of 3 DC Distribution Engineering Standard VZ-STD-26.33.10This Document Supersedes VZ-292-100-000 and VZB STD-022-0003REVISION 1.0ISSUED OCTOBER 21, 2011CONTENTS PAGE1.1. Purpose and Scope1.2. Disclaimer1.3. Regulated and Non-Regulated Facilities1.4. Additional Standards Requirements1.5. Approved Products 2.1. Running Direct Feeds from Power Plants or Using a Secondary Power Source2.2. Intermediate Distribution Bays and Intermediate Fuse Panels2.3. Feeding Equipment from the Main Power Board or BDFB2.4. Design for Maximum Current Drains3.1. Voltage Drop Arrangements and Calculations3.3. Voltage Drop Calculation Formulas3.4. DC Power Cable3.5. RHH /RHW Power Cable Calculation Information3.6. Minimum Conductor Gauge based upon Circuit Breaker or Fuse Size3.7. Maximum Allowable Ampacity Based Upon Cable Size3.8. Power Cable Connectors3.8.1. General Use Compression Lug Requirements3.8.2. Taps and Splices3.9. Discharge Ground and Ground Window Term Bars3.10 Over Current Protective Devices3.11. Over Current Device Coordination and Sizing3.12. Diversity3.13. DC Cable Routing and Segregation4.1. General5.1. General5.2. BDFB (BDCBB) Requirements5.3 Equipment Powering Schemes5.4 Powering ORd EquipmentFigure 8: ORd Method 15.5 Load Balancing Simplex and Duplex Power5.6 Relay Rack Equipment Fuse/Breaker Panels5.7 Monitoring and Alarming5.7.1 Main Power Board Current Drain Monitoring5.8 Battery Returns in BDFBs5.9 Power to Collocated Equipment7.1 General7.2 Telcordia Documents7.3 Industry Documents and Standards